Imam Saheed, Fitzgerald Colin M, Cook Emily M, Donohue Timothy J, Noguera Daniel R
Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI, USA.
Photosynth Res. 2015 Feb;123(2):167-82. doi: 10.1007/s11120-014-0061-1. Epub 2014 Nov 27.
Obtaining a better understanding of the physiology and bioenergetics of photosynthetic microbes is an important step toward optimizing these systems for light energy capture or production of valuable commodities. In this work, we analyzed the effect of light intensity on bioproduction, biomass formation, and maintenance energy during photoheterotrophic growth of Rhodobacter sphaeroides. Using data obtained from steady-state bioreactors operated at varying dilution rates and light intensities, we found that irradiance had a significant impact on biomass yield and composition, with significant changes in photopigment, phospholipid, and biopolymer storage contents. We also observed a linear relationship between incident light intensity and H2 production rate between 3 and 10 W m(-2), with saturation observed at 100 W m(-2). The light conversion efficiency to H2 was also higher at lower light intensities. Photosynthetic maintenance energy requirements were also significantly affected by light intensity, with links to differences in biomass composition and the need to maintain redox homeostasis. Inclusion of the measured condition-dependent biomass and maintenance energy parameters and the measured photon uptake rate into a genome-scale metabolic model for R. sphaeroides (iRsp1140) significantly improved its predictive performance. We discuss how our analyses provide new insights into the light-dependent changes in bioenergetic requirements and physiology during photosynthetic growth of R. sphaeroides and potentially other photosynthetic organisms.
更好地理解光合微生物的生理学和生物能量学是优化这些系统以进行光能捕获或生产有价值产品的重要一步。在这项工作中，我们分析了光强度对球形红细菌光异养生长过程中的生物生产、生物质形成和维持能量的影响。利用从以不同稀释率和光强度运行的稳态生物反应器中获得的数据，我们发现辐照度对生物质产量和组成有显著影响，光合色素、磷脂和生物聚合物储存含量发生了显著变化。我们还观察到在3至10 W m(-2)之间入射光强度与H2产生速率之间存在线性关系，在100 W m(-2)时观察到饱和现象。在较低光强度下，光转化为H2的效率也更高。光合维持能量需求也受到光强度的显著影响，这与生物质组成的差异以及维持氧化还原稳态的需求有关。将测量的条件依赖性生物质和维持能量参数以及测量的光子摄取率纳入球形红细菌的基因组规模代谢模型（iRsp1140）中，显著提高了其预测性能。我们讨论了我们的分析如何为球形红细菌以及潜在的其他光合生物光合生长过程中生物能量需求和生理学的光依赖性变化提供新的见解。
